The present invention relates to a thermal spraying system for a cylinder and, more particularly, to a thermal spraying system for a cylinder, which carries out thermal spraying on the bore inside surface of a cylinder by holding the cylinder on a turntable and by moving a thermal spraying gun in the axial direction in the bore of the cylinder while the cylinder is rotated.
In thermal spraying for a cylinder in mass production, to form a deposit while dust is sucked from the lower face of bore by using the dust discharge pipe is an important technology in terms of prevention of dust from being entrained in the deposit. However, unless measures are taken against accumulation of spray deposit on the connecting jig and the dust discharge pipe connecting portion (suction port), the deposit accumulating on the connecting jig and the dust discharge pipe suction port degrades the property of deposit formed on the inside surface of a cylinder, or results in the peeling-off of the deposit.
The present invention has been made in view of the above situation, and accordingly an object thereof is to provide a shape of a dust discharge pipe suction port and constructions of a dust discharge pipe and the suction port thereof which are less liable to permit a spray deposit to accumulate to accomplish thermal spraying of cylinders continuously, and to provide a thermal spraying system for a cylinder which is suitable for mass production of cylinders to accomplish thermal spraying of cylinders continuously.
Specifically, in accordance with the present invention there is provided a thermal spraying system for a cylinder, in which
a cylinder is held on a turntable;
a bore inside surface of said cylinder is subjected to thermal spraying by moving a thermal spraying gun in the axial direction in the bore of said cylinder while said cylinder is rotated;
a suction port of a dust discharge pipe for sucking dust in the bore of said cylinder is disposed under said cylinder to suck and discharge dust in the bore of said cylinder; and
the diameter of the suction port of said dust discharge pipe is larger than the inside diameter of the bore of said cylinder.
According to the thermal spraying system for a cylinder in accordance with the present invention, the flow of spray flame and dust is discharged smoothly without being obstructed by the dust discharge pipe, and spray flame is blocked by the lower end inside surface of the cylinder bore, so that a deposit is not formed on the suction port of the dust discharge pipe. Therefore, the spray deposit on the lower end inside surface of the cylinder bore and the spray deposit on the suction port of dust discharge pipe do not connect with each other, and also when a cylinder having been subjected to thermal spraying is removed from the dust discharge pipe, there is no fear of damaging the spray deposit on the lower end inside surface of the cylinder bore.
It is advantageous an angle between the center axis of spray flame injected from said thermal spraying gun and said dust discharge pipe is 45 degrees or less.
With this feature, a spray deposit is prevented from adhering to the dust discharge pipe to the utmost. Therefore, the dust discharge pipe need not be replaced, so that a mass production effect can be achieved, and also a stable spray deposit can be formed.
It is also advantageous that said dust discharge pipe is divided into a rotating portion and a fixed portion, and said rotating portion is held integrally with said turntable and is inserted in said fixed portion with a gap therebetween.
With these features, since the dust discharge pipe is rotated, the flame does not hit only a part of the dust discharge pipe. Therefore, the dust discharge pipe is prevented from being melted by the spray flame, and the spray deposit is formed so as to be distributed on the inside surface of the dust discharge pipe, so that the deposit forming speed is low, and the flow of dust discharge is not obstructed. Also, since the dust discharge pipe is held integrally with the turntable, special power for rotating the dust discharge pipe is not needed. Further, since the rotating portion of the dust discharge pipe is inserted in the fixed portion with a gap therebetween, and a bearing or the like need not be provided, there is no need for taking measures to protect the bearing or the like against heat.
It is also advantageous that a rotating shaft of said turntable is formed of a tube, and said dust discharge pipe is disposed in said rotating shaft with a gap therebetween.
With these features, since the dust discharge pipe and the rotating shaft of turntable are disposed with a gap therebetween, heat of the dust discharge pipe is scarcely transmitted to the rotating shaft of turntable, so that grease for a bearing or the like for holding the rotating shaft of turntable, sealing portion, and the like are not influenced thermally, whereby the durability is enhanced.
It is also advantageous that said cylinder is fixed to a pallet, said pallet is conveyed and fixed to said turntable;
said cylinder is rotated together with said pallet;
U-shaped rails for guiding said pallet are provided in parallel above said turntable so as to be movable vertically; and
pins are erected on said turntable and holes are formed in said pallet;
so that said pallet to which said cylinder is fixed is guided by said U-shaped rails and said U-shaped rails are lowered to fit the holes formed in said pallet on said protrusions provided on said turntable;
whereby said cylinder is positioned and locked on said turntable.
With these features, the construction is simple, the maintainability is high, and excellent durability is obtained. Moreover, the cylinder can easily be positioned and locked on the turntable, and also even if the power such as air is shut off during the rotation of turntable, the pallet is not unclamped.